Lubricating greases



s,oo2,742 LUBRTCATING GREASES Samuel Richard Pethrick and AleksanderGroszek, Sun

United States Patent r 3,662,742 Patented Nov. 6, lfi2 ice metalalcoholate to form a metaloxy fatty acid ester, and hydrolizin-g thelatter material with a metal hydroxide, e.g. in part or all of the oilto be thickened, the grease Thickening agent precursor.

bury-on Thanres, England, assignors to The British Pe- 5 am 1.

c g thereafter formed 1n known manner. A particular- 7 n!jtgtgilgusrtrciorcrggrgazfiitw, London, England, a Bmlsh 1y suitableester is hydrogenated castor 011 which consists N Drawing Filed Mar. 3,1959, Ser. No. 796,775 essentially of glyceryl tr1-l2-hydroxystearate.The use Claims priority, application Great Britain Man g of esters, suchas hydrogenated castor 011, prov1des the 13 Claims. (CL 252 41) simplestand cheapest method of producing greases ac- 1O cording to theinvention, but the use of fatty acids or Thi i ti l t t lubricatinggreases fatty acid soaps as starting materials has the advantageAccording to th invention a lubricating grease mthat the greases formeddo not contain any glycerol which position comprises a lubricating oilthickened to a grease is present in greases prepared from hydrogenatedcaster consistency with a thickening agent comprising a metaloils. oxyfatty acid soap. The lubricating oil is preferably 15 The amount of soappresent in the grease compositions amineral lubricating oil. accordingto the invention is preferably 5 to 30% by By metaloxy fatty acid soapis meant a fatty acid soap weight especially 8 to 15% by weight. inwhich at least one carbon atom of a hydrocarbon A number of thickeningagents were prepared, by way chain (R) of the soap is attached to anoxygen atom of eXample,inthe following manner: which is also attached tometal. The said metal is pref- Thickening agent Pflicllfsofs S3 and 34erably a metal which forms an alcoholate, especially a l 1 below) were pp from y y lithium, sodium, barium or aluminium. Where it is a hy r ythe r of hy r g d a r polyvalent metal it may be attached via oxygenatoms il). The hydrogenated Cas r i Was Placed to more than onehydrocarbon radical of a soap. Th in a flask, fitted with a stirrer andthermometer, and said hydrocarbon radical or radicals may contain onemelted. The calculated Weight of lithium or sodium was or more othersubstituent groups, e.g. a hydroxyl group. then added and thetemperature raised until the reaction The fatty acid soaps arepreferablythose of the formm n t pp ly n then kept at mula (RCOO) ,,X(OI-l) whereR is a hydrocarbon or a temperature between 200 and 250 C. until thereaction substituted hydrocarbon radical, preferably having 1230 0 wascomplete.

carbon atoms; X is any soap-forming metal or group, Thickening agentprecursor S5 was prepared by addespecially an alkali or alkaline earthmetal, magnesium mg lithium ethoxide to molten hydrogenated castor oil.or aluminium, x is the valency of X and n is 0 or a num- The mixture Washeated with stirring at 200 C. and ber smaller than x. the alcoholforming in the course of the reaction was It is to be understood thatthe grease consistency may or allowed to distil off. The alcoholremaining in solution be obtained by the use of a mixture of differentmetalin the oil on completion of thereaction was removed oxy fatty acidsoaps or a mixture of metaloxy soap and by the application of a vacuum.other soaps, e.g. hydroxy fatty acid soaps. Thickening agent S6 wasprepared from l2-hydroxy v The thickening agent may conveniently beprepared by stearic acid and lithium. The reaction was conductedreacting a hydroxy fatty acid, or a soap thereof, with a 40 undernitrogen. Small proportions of finely dispersed metal or metalalcoholate. A particularly suitable hylithium were added to the moltenacid which was maindroxy acid is IZ-hydroxy stearic acid. The productsobtained at a temperature of 220 C. The mixture was tained in this waycan be used directly for the preparation vigorously stirred throughoutthe addition until each porof greases by known methods, e.g. by heatinga mixture tion had reacted completely. After the last portion of of oiland thickening agent to a temperature at which lithium had been added,the reaction was completed by complete solution takes place (usuallyabout 200 C.) heating at 250-260 C. for 1 /2 hours. and thereaftercooling rapidly to room temperature. The reactants used, temperature ofreaction and data Alternatively, the thickening agent may 'beformed-by"- on the products in each case are given in Table 1.

Table 1 Reaotants Used Temper- Setting Thickening aturc of Point ofAgent 7 reaction, Product, Appearance of Product Remarks Metal HydroxyAcid 0. C.

or Ester S1 Lithium, 1.88 g 400 g. H00... 230 Greenish brown, opaque,Reaction complete in 34 soft greasy material. hours.

S2 Lithium, 6.7 g 400 g. 1100... 230 170 Light brown, opaque,soft,Reaction not complete in '6 amorphous solid. hours of heating.

S3 Lithium, 3.6 g. 400 g. H00." .220 160 Lighfz ioaown, opaque, Reactioncomplete in 6-8 SO SO 1 01] S.

S4 Sodium, 0.8 g 400 g. HCO 210 150 Light brown, opaque, Reactioncomplete in 3-4 waxy solid. hours.

S5 Lithiumethoxido, 400 g. 1100... 200 Straw coloured moder- Do.

11.5 g. itchy soft, wax-like,

S6 Lithium, 2.8 g g. HSA... 220 190 Hardfhrittle, translucent Reactionbegins at 0. solid, light brown in Most; of the lithium reacts colour.at 220 C. and the last traces of lithium are eliminated by heating to250- 260 0.

'IZ-hydroxy stearic acid.

The products of the reactions were then used for the preparation ofgreases G1-G6 (see Table 2), the procedure being as follows:

G1, G2 and G4: A mixture consisting of 200 g. each of acid-treatedmineral lubricating oils having Redwood 1 viscosities at 140 F. of 140and 50 seconds respectively was heated to 75 C. 400 g. of the thickeningagent were then added followed by 46.2 g. lithium hydroxide monohydratedissolved in 400 ml. of water at 65 C. The mixture was gradually heatedto 120 C., 800 g. of the same mixture of oils were added and thetemperature raised to 137 C. Subsequently, a mixture consisting of 140parts of 160/95 oil (160 Redwood 1 seconds at 140 F. and viscosity indexof 95) and 560 parts of a bright stock oil (620 Redwood 1 seconds at 160F. and viscosity index of 95) were added and heating was continued tillapproximately 170 C. was reached. The mixture was then cooled to 135 C.,poured, and milled through a roller mill at 0.003 inch gap.

G3 and G5: The method was the same as for G1, G2 and G4 but the oil usedhad a Redwood 1 viscosity at 140 F. of 150 seconds.

G6: The thickening agent was dissolved with stirring in a lubricatingoil having a Redwood 1 viscosity at 140 F. of 150 seconds. The solutionwas cooled rapidly to room temperature, milled as before and deaerated.

By way of comparison, a lithium 12-hydroxy stearate grease (G7) wasprepared as follows:

G7: A mixture consisting of 200 g. each of acid treated minerallubricating oils having Redwood 1 viscosities at 140 F. of 140 and 50seconds respectively was heated to 75 C. 400 g. of hydrogenated castoroil were added followed by 58 g. of lithium hydroxide monohydratedissolved in 600 ml. of water at 65 C. The heating was continued and thetemperature of the mixture raised to 90 C. whereupon another 100 ml. ofwater were added. Themixture was heated to 120 C., 800 g. of the samemixture of oils were added and the temperature raised to 137 C.Subsequently a mixture consisting of 140 parts of 160/95 oil 160 Redwood1 seconds at 140 F. and viscosity index of 95) and 560 parts of a brightstock (620 Redwood 1 seconds at 160 F. and viscosity index of 95) wasadded and heating continued till approximately 190 C. was reached. Themixture Was then cooled to 135 C., poured, and milled through. a rollerat 0.003 inch gap.

The composition and properties of the greases are given in Table 2.

4 tion (GI-G6) have good drop points and consistency. They also havemuch improved resistance to bleeding than the lithium hydroxy stearategrease (G7). Greases G1-G6 also contain less soap than grease G7.

Greases G1-G6 all had a very good texture, G6 in particular being a verysmooth grease.

A rig test was carried out on grease G4 at ambient temperature using aroller bearing, mm. x mm. x 46 mm., rotating at a speed of 2500 r.p.m. Aload of 851 kg. was applied radially and the direction of rotationchanged every 24 hours. The total time of the test was 200 hours. Thebearing was tested for wear on the tracks, rollers and cage and theassembly was checked for absence of leakage of the grease. No adverseefiects were noted.

The same rig test was carried out on grease G6 but for a period of 667hours. The result again was a very good pass.

We claim:

1. A method of preparing a lubricating grease in which a saponifiablehydroxy fatty acid ester is reacted with a metalating agent selectedfrom the group consisting of the alkali metals and their alcoholates, toproduce a metaloxy compound, and in which the said metaloxy compound isdissolved in a lubricating oil and saponified by reacting the solutionwith a soap-forming metal base whereby the lubricating oil is thickenedto a grease consistency.

2. A method according to claim 1, in which the hydroxy fatty acid esteris a glyceride.

.3. A method according to claim 1, in which the lubricating oil isamineral oil.

-4. Amethod according to claim 1, in which the hydroxy fatty acidcontains 12-30 carbon atoms.

5. A method according to claim 1, in which the soapforming metal base isan alkali metal base.

6. A method according to claim 5, in which the alkali metal base islithium hydroxide.

7. A method according to claim 1, in which the hydroxy fatty acid esteris an ester of 12-hydroxy stearic acid.

8. A method according to claim 1, in which the hydroxy fatty acid esterrepresents 5-30% by weight of the final composition.

9. A method according to claim 1, in which the hydroxy fatty acid esterrepresents 815% by weight of the final composition.

Table 2 Components of Grease Properties of Greases Grease Penetration at70 F. Bleeding Number Test Drop Thickening Oil, g. M011. 1120, (DTD825). Point Agent g. 60 100,000 Oil loss: C.

Unworked Strokes Strokes percent weight 400 g. S1" 215 217 262 0.8 186400 g. S2 171 163 228 0.2 191 400 g. S3 284 309 265 nil g. 220 225276 1. 9 187 400 g. S5 218 219 262 0.2 188 S6 88 200 252 332 1.1 187 400g. HCO* 2, 500 58 246 295 2. 4 190 Hydrogenated castor oil. Thickeningagent precursor.

Penetration (IP method 50/56) is a measure of the 10. A method ofpreparing a lubricating grease in consistency of a grease. The BleedingTest (Ministry of 70 which an ester of 12-hydroxy stearic acid isreacted with Supply Specification DTD 825A) indicates the tendency ofthe liquid phase (oil) to separate from the grease structure. Drop point(IP method 31/57) gives the temperature at which a grease becomes fluid.

It will be seen that the greases according to the invena metalatingagent selected from the group consisting of lithium and its alcoholates,to produce a lithoxy compound, and in which the said lithoxy compound isdissolved in a lubricating oil and saponified by reacting the solutionof lithoxy compound in lubricating oil with lithium hydroxide wherebythe lubricating oil is thickened to a grease consistency.

11. A method according to claim '10, in which the ester of 12-hydroxystearic acid is a glyceride.

12. A method of preparing a lubricating grease in which an ester of12-hydroxy stearic acid is reacted with a metalating agent selected fromthe group consisting of sodium and its alcoholates, to produce a sodoxycompound, and in which the said sodoxy compound is dissolved in alubn'cating oil and saponified by reacting the solution of sodoxycompound in lubricating oil with lithium hydroxide whereby thelubricating oil is thickened to a grease consistency.

13. A method according to claim 12, in which the ester of 12-hydroxystearic acid is a glyceride.

6 References Cited in the file of this patent UNITED STATES PATENTS2,445,935 Bondi July 27, 1948 2,469,041 Jones May 3, 1949 2,582,833 HunnJan. 15, 1952 2,651,616 Matthews et a1. Sept. 8, 1953 2,883,342 Sprouleet a1. Apr. 21, 1959 2,890,232 Rogers et al. June 9', 1959 2,957,009Holmguist et a1 Oct. 18, 1960 OTHER REFERENCES Organic Chemistry,Karrer, Elsevier Pub. Co., Inc., N.Y., London, 1947, page 84.

1. A METHOD OF PREPARING A LUBRICATING GREASE IN WHICH A SAPONIFIABLEHYDROXY FATTY ACID ESTER IS REACTED WITH A METALATING AGENT SELECTEDFROM THE GROUP CONSISTING OF THE ALKALI METALS AND THEIR ALCOHOLATES, TOPRODUCE A METALOXY COMPOUND, AND IN WHICH THE SAID METALOXY COMPOUND ISDISSOLVED IN A LUBRICATING OIL AND SAPONIFIED BY REACTING THE SOLUTIONWITH A SOAP-FORMING METAL BASE WHEREBY THE LUBRICATING OIL IS THICKENEDTO A GREASE CONSISTENCY.